Design And Manufacture Of Generalized Flow Profile-Producing Devices

ABSTRACT

The present invention provides a process for making a flow conditioning device that transforms an input flow into a desired output flow. The process includes the steps of inputting into a computer program a set of design constraints representative of the input flow and the output flow. The computer program generates a design representative of a flow-conditioning device that transforms the input flow into the output flow. The process then provides the output design to an additive manufacturing or other suitable production system adapted to form a solid representation of the flow-conditioning device.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/022,868 filed Jul. 10, 2014 and herein incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH & DEVELOPMENT

This invention was made with government support under Contract No.NNL09AA00A awarded by the National Aeronautics and Space Administration.The government has certain rights in the invention.

INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION

In many fluids applications, a flow-conditioning device that can producea desired flow field is needed. Current methods applied to aircraftengines typically produce total pressure profiles by means of wire-meshscreens. Segments of varying porosity wire-meshes produce differentamounts of total pressure losses depending on the porosity of the screenand the inlet flow conditions.

The performance of wire-mesh screens is difficult to predict, andconstruction of a device is limited to available wire-mesh porosities.The result is that multiple wire-mesh screens are often designed,constructed, and tested before the desired total pressure profile isachieved. Often, even after multiple iterations, the resulting profiledoes not match the desired profile due to wire-mesh porosityavailability.

Other current methods produce swirl (or velocity) profiles by means ofguide vanes. These vanes turn the flow from one direction to another.The possible flow velocity profiles are limited by the manufacturabilityof the guide vanes. In all cases, guide vanes are only capable ofproducing relatively simple swirl profiles.

Thus, for the aircraft engine applications there is a need for a methodin which a detailed, complex flow field may be created by aflow-conditioning device. This is especially true for commercialaircraft designers, which have avoided the problem of inlet flowdistortion by placing engines away from the airframe in the free stream.As airframe designers have sought even higher performance, they havebeen led to designs such as blended wing or hybrid wing body aircraftthat promise increased fuel economy when compared to traditional tubeand wing designs. These designs can present distorted inflows to thepropulsion engine.

Military aircraft have long been forced to deal with the problem ofdistorted inflow. The desire for low observability has led airframedesigners to choose predominantly embedded engines on military aircraftsuch as fighter jets and UAVs. Related to this, there is a provenmethodology for testing engine response to arbitrary total pressuredistortion profiles. Along with this distortion creation methodology,there is also a standard for quantifying total pressure distortion, asdescribed in SAE Recommended Practice ARP 1420.

In addition to the aircraft engine application, the present inventionmay be used in any fluid flow application where a specified complex flowfield is required or desired.

BRIEF SUMMARY OF THE INVENTION

In one embodiment, the invention provides a method of making aflow-conditioning device such as a guide vane or airfoil for use in anyapplication in which a detailed, complex flow field is desired. In thiscontext, a flow field may consist of the total pressure and velocitydistributions of the flow in a region. The velocity distributions mayinclude local velocity magnitudes as well as flow direction (swirl).

In another embodiment, the present invention provides a method for thedesign and manufacture of flow profile-producing devices. The methodutilizes computational procedures for the aerodynamic and mechanicaldesign of a device that can alter a given incoming flow profile to adesired outlet flow profile.

In yet other embodiments, the present invention can achieve outlet flowprofiles that may consist of any desired velocity field, including bothaxial and swirl components. In other embodiments, the flow conditioningdevices of the present invention are designed using computationalmethods that optimize the geometry for its purpose.

In yet other embodiments, the present invention can produce arbitraryswirl combined with arbitrary total pressure profiles.

In other aspects, the present invention provides design approaches tothe design of the flow-conditioning device, which may include: (1) themethod of predicting/designing total pressure losses, (2) the vaneplacement scheme, and (3) the use of predicted downstream flowdevelopment to iteratively design the profile at the screen plane.

The advantages of the invention include, but are not limited to (1) theability to produce a desired flow pattern directly from a CFD analysis,(2) the ability to produce any arbitrary total pressure profile, (3) theability to produce any arbitrary swirl profile, (4) the ability toproduce a combined total pressure and swirling flow profile (impossiblein current practice), (5) improved accuracy in the profile that thedevice produces compared to current methods, and (6) reduced time andexpense compared to current methods.

The invention produces both the total pressure losses and swirl profilesvia specially designed vanes. However, these vanes differ fromtraditional guide vanes in that they are locally tailored to produce acertain swirl and total pressure loss. The freedom to produce morecomplex geometries allows the vanes to locally change in angle, chordlength, and thickness. These parameters provide infinitely variabledesign control over total pressure and swirl angles at each local pointin the flow. Thus, combined total pressure and swirl profiles arepossible where traditional methods fail.

The methodology of the present invention may also be applied to creatingflow-conditioning devices for commercial aircraft that may lead to anairframe-engine system without operability problems. To do so, themethodology allows for testing the effect of advanced airframe designson engines, and potentially designing distortion-tolerant fans, usingboth total pressure and swirl. In other embodiments, the presentinvention allows engine and airframe manufacturers to examine theresponse of engines to new distortion environments within a highfidelity, controlled, test environment.

Additional objects and advantages of the invention will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages of the invention will be realized and attained bymeans of the elements and combinations particularly pointed out in theappended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe substantially similar components throughout the severalviews. Like numerals having different letter suffixes may representdifferent instances of substantially similar components. The drawingsillustrate generally, by way of example, but not by way of limitation, adetailed description of certain embodiments discussed in the presentdocument.

FIG. 1 is a vector plot of NASA Inlet-A, a profile from a boundary layeringesting, embedded inlet. The solid lines are everywhere parallel tothe flow while the dashed lines are everywhere perpendicular.

FIG. 2 is an isometric view of a stream vane design formed to producethe NASA Inlet-A profile, showing the leading edge blade lines, thenumerous defining blade profiles lines beneath each blade line, and thetrailing edge blade line which is formed by the end of the bladeprofiles.

FIG. 3 shows a solid geometry formed from the blade geometry describedin FIG. 2.

FIG. 4 shows a flow-conditioning device designed to reproduce the NASAInlet-A flow profile printed in ABS plastic.

FIG. 5 shows a vector plot of NASA Inlet-A, a profile from a boundarylayer ingesting, embedded inlet. The solid lines are everywhere parallelto the flow while the dashed lines are everywhere perpendicular.

FIG. 6 shows a plot of swirl angle from a screen designed to produce asingle bulk vortex. These data were derived from stereoscopic PIV data.

DETAILED DESCRIPTION OF THE INVENTION

Detailed embodiments of the present invention are disclosed herein;however, it is to be understood that the disclosed embodiments aremerely exemplary of the invention, which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention in virtually any appropriately detailedmethod, structure or system. Further, the terms and phrases used hereinare not intended to be limiting, but rather to provide an understandabledescription of the invention.

In one embodiment, the methodology of the present invention uses severalbasic approaches. First, it takes into account that a flow turningdevice is effective when it is placed perpendicular to the desiredturning direction. Second, it may use experimental data from theliterature, and/or CFD simulations, and applying this information,produce a turning by a cascade of airfoils based on prediction.Combining these two concepts, the present invention in one embodiment,creates rows of turning vanes everywhere perpendicular to the desiredflow turning direction. This produces a flow turning device geometrythat may be reproduced using additive manufacturing or similartechniques.

In inlet flow distortion analysis, the goal is to duplicate the desiredflow in a real installation at a designated plane, termed theAerodynamic Interface Plane or AIP. This plane serves as the couplingbetween airframe and engine. Once the desired three-component velocityprofile is chosen at the AIP, the stream vane creates the desiredvelocity profile at its trailing edge from an assumed uniform inletvelocity profile. FIG. 1 shows a plot 100 of velocity vectors taken fromthe flow profile of NASA Inlet-A, which is a boundary layer ingestingembedded inlet. In FIG. 1, the solid lines, some of which are designatedas 101-104, are everywhere parallel to the in-plane flow, while thedashed lines, some of which are designated as 106-109, are everywhereperpendicular.

The present invention then moves along each of these perpendicular linesto calculate the distance to at least one adjacent line. In otherembodiments, the present invention calculates the distance to thenearest or two nearest neighboring lines at regular intervals. Alongwith calculating the vane's spacing, the original vector field is alsoqueried to find the desired turning angle at each blade location. Usingtabulated linear cascade data, the present invention then determines thevane angle of attack and camber line needed to produce the desiredturning. The present invention controls vane solidity by using thepreviously calculated vane spacing and varying the chord.

The blade profiles and blade lines may then be exported to a CADpackage. FIG. 2 shows the vane lines and profiles after they have beenexported. FIG. 2 shows leading edge blade lines, some of which areidentified as 200-202, a plurality of defining blade profile linesbeneath each blade line, some of which are identified as 203-205, andthe trailing edge blade line which is formed by the end of the bladeprofiles, such as 206.

The blade profiles are then swept along their corresponding vane linesto create solid bodies. These solid blade bodies are then joined atvortex centers and structure and flanging is added as needed. A CADmodel of a completed flow-conditioning device such as a screen is shownin FIG. 3.

In other embodiments, the solid geometry is used to create a physicaldevice. The geometry may be used with additive manufacturing or asimilar technique to create a flow-conditioning device. FIG. 4 shows aswirl screen designed to produce NASA Inlet-A flow distortion after ithas been printed in ABS plastic. This particular model was produced tobe tested in a low speed wind tunnel.

In yet other embodiments, the present invention relies on severalassumptions. First, the present invention considers that the flow arounda single vane will be the same as it is downstream of a row of vaneswith the same solidity, angle of attack, and vane shape. This allows theflow-conditioning device to be considered as consisting of many bladerows similar to linear cascades.

As also shown in FIG. 5, plot 500 show how the vanes would be positionedalong each dashed line, some of which are designated 501-504. One canthen think of slicing the vanes along the solid lines, some of which aredesignated 505-508, parallel to the flow so as to produce a series ofindependent vanes, similar to a linear cascade. Unlike a linear cascadehowever, each of the vanes is designed for a different amount ofturning. Another consideration is that the desired output turning of onevane will be close enough to that of its neighbors that it will stillcreate turning similar to what it would if its neighbors were all likesof itself. This allows for the determination of what blade to use ineach location by using linear cascade data.

The present invention may also assume that flat plate blades will behavesimilarly to those with an airfoil thickness profile. Even thoughadditive manufacturing provides flexibility when it comes to whatgeometries can be created, there are still limitations to what can bemade, especially with regard to very small features. To overcome thesmall features that would be present at the leading and trailing edgesof flow-conditioning device such as airfoils, the present invention usesa thickness profile around the chamber line that is a simple flat platewith rounded leading and trailing edges. However, as additivemanufacturing and other manufacturing methods improve, more complex andhigher fidelity airfoil shapes may be produced.

In order to test the effectiveness of the present invention, aflow-conditioning device was tested in a wind tunnel to test the swirldistortion generation. The tunnel produced 50 m/s flow in a 6 inchdiameter test section.

This tunnel can be set up in several different ways to provide flowmeasurements behind a distortion-generating device. The firstconfiguration consists of a screen mounted in a rotating bearing drivenby a stepper motor, along with a probe mounted in a linear traversesystem.

The traverse system is composed of two linear traverses. The first oneplunges the probe radially, while the second traverse moves the firstand the probe axially; positioning the probe nearer or further from thescreen. The traverse system can accept many different types of probessuch as a pitot probe, pitot-static probe, multihole direction pressureprobe, or hotwire probe. Combining the two linear traverse systems andthe capability of the screens ability to rotate, the flow field can bemeasured at any location in the 3-dimensional volume downstream of thescreen. This has proven to be useful by providing an easy andinexpensive way to test both total pressure and swirl distortiongeneration devices.

A second configuration allows flow behind a test screen to be measuredusing two cameras, using stereoscopic Particle Image Velocimetry (PIV).This configuration has the capability to measure all three components ofvelocity in any plane downstream of the screen all at once and in veryfine detail. The equivalent traverse program would take much longer totake the equivalent measurements.

FIG. 6 shows a representative dataset acquired using this configuration.In order to test the instrumentation and manufacturing method of thepresent invention, a swirl distortion screen was designed to producesingle bulk vortex pattern. FIG. 6 shows a plot of the swirl anglesproduced by a bulk swirl screen as derived from the stereoscopic PIVmeasurements taken four diameters downstream of the screen.

In other embodiments, the present invention provides a swirl distortiongeneration method capable of reproducing any desired swirl distortionprofile. Along with the screen development method, a low speed tunnelcapable of verifying the accuracy of the design is also provided.

In yet further embodiments, the present invention provides three flowstations that are defined as follows. Station 1 (the “inlet station”)refers to the flow plane that enters the device. Station 2 (the device“outlet station”) refers to the flow plane at the trailing edge of thedevice. Finally, Station 3 (the “instrumentation station”) refers to theflow plane at which a certain profile is desired. This embodimentachieves the alteration of an incoming flow field by means of guidevanes that are locally optimized to produce the desired total pressurelosses and flow turning as follows.

A known flow profile enters the device at Station 1. The local vanegeometries produce total pressure losses and turning effects on the flowbefore it leaves the device at Station 2. By predicting the developmentof a complex flow field downstream of the device, the resulting profileat Station 3 is estimated. Following an iterative design method, thegeometry of the device is altered until the desired Station 3 profile isachieved.

Prediction of downstream flow development is performed using vortextheory and computational fluids methods. The flow leaving the devicewill continue to develop and change profile as it flows. When a finitedistance places the device upstream of the instrumentation plane, theflow reaching the instrumentation plane will be altered with respect tothe flow leaving the device. Prediction of this flow alteration enablesthe iterative design of a device that produces the desired flow profileat the instrumentation plane by including downstream flow developmenteffects.

The device is typically manufactured using additive manufacturing (3Dprinting) techniques, although other manufacturing techniques can beemployed. With additive manufacturing, complex geometries can beproduced to high levels of accuracy with no additional cost associatedwith complexity. In addition, the geometry of the device is not limitedby traditional manufacturing techniques. By removing the “design formanufacture” constraints, geometries that are truly optimized for theirpurpose are possible.

In still further embodiments of the present invention, a process formaking a fluid flow guide vane that transforms an input flow into adesired output flow is provided. The method is comprised of thefollowing steps: 1) obtaining an array of desired velocity vectors fromcomputational fluid dynamics or measurements from an experiment withinthe input flow; 2) creating lines on a plot representing lineseverywhere parallel to the input flow; 3) creating vane lines on theplot represented by lines everywhere perpendicular to said parallellines; 4) querying the input vector field to determine a turning anglethat transforms the input flow into the desired output flow along thevane lines; and 5) using the turning angle to determine a vane geometrythat transforms the input flow into the output flow at the vane lines.The vane geometry may then be outputted to an additive manufacturingsystem adapted to form a solid representation of the vane geometry atthe vane lines or the vane geometry is outputted to any suitablemanufacturing system adapted to form a solid representation of the vanegeometry at the vane lines.

In other embodiments, the perpendicular lines are spaced at regularintervals. In addition, a seed line is used to create a first parallelline and the vane lines are created at predetermined intervals along theseed line. The method may also include a vane model that creates a vanegeometry for the vane lines by using parameters including the distanceto the nearest two vanes lines and the desired vane thickness andsolidity.

In still further embodiments, a process for making a flow-conditioningdevice that transforms an input flow into a desired output flow isprovided. The process comprising the steps of inputting into a computerprogram a set of design constraints representative of the input flow andthe output flow, thus generating an output design representative of aflow conditioning device that transforms the input flow into the outputflow and providing the output design to an additive manufacturing orother suitable production system adapted to form a solid representationof the flow conditioning device.

In some embodiments, the computer program is a computational fluiddynamic program. Also, the design constraints representative of theinput flow and output flow are comprised of pressure and velocitydistributions. In other embodiments, a design constraint places thefluid control device perpendicular to the fluid flow or places the fluidcontrol device everywhere perpendicular to the local fluid flow. Instill further embodiments, the design constraints are 1) representativeof the input are comprised of pressure and velocity distributions, 2)representative of the output are comprised of pressure and velocitydistributions and 3) place the fluid control device everywhereperpendicular to the fluid flow. Also, the computational fluid dynamicprogram may be adapted to make local design changes in angle, chordlength and location, and thickness to create a final vane design.

While the foregoing written description enables one of ordinary skill tomake and use what is considered presently to be the best mode thereof,those of ordinary skill will understand and appreciate the existence ofvariations, combinations, and equivalents of the specific embodiment,method, and examples herein. The disclosure should therefore not belimited by the above described embodiments, methods, and examples, butby all embodiments and methods within the scope and spirit of thedisclosure.

What is claimed is:
 1. A process for making a fluid flow guide vane thattransforms an input flow into a desired output flow comprising the stepsof: obtaining an array of desired velocity vectors from within the inputflow; creating lines on a plot representing lines everywhere parallel tosaid input flow; creating vane lines on said plot represented by lineseverywhere perpendicular to said parallel lines; querying the inputvector field to determine a turning angle that transforms the input flowinto the desired output flow along the vane lines; using said turningangle to determine a vane geometry that transforms the input flow intothe output flow at said vane lines.
 2. The method of claim 1 whereinsaid vane geometry is outputted to an additive manufacturing systemadapted to form a solid representation of the vane geometry at said vanelines.
 3. The method of claim 1 wherein said vane geometry is outputtedto a manufacturing system adapted to form a solid representation of thevane geometry at said vane lines.
 4. The method of claim 1 wherein saidperpendicular lines are spaced at regular intervals.
 5. The method ofclaim 1 wherein a seed line is used to create a first parallel line andsaid vane lines are created at predetermined intervals along said seedline.
 6. The method of claim 1 wherein a vane model creates a vanegeometry for said vane lines by using parameters including the distanceto at least one adjacent vane line.
 7. A process for making a flowconditioning device that transforms an input flow into a desired outputflow comprising the steps of: inputting into a computer program a set ofdesign constraints representative of the input flow; inputting into acomputer program a set of design constraints representative of theoutput flow; generating an output design representative of a flowconditioning device that transforms the input flow into the output flow;and providing said output design to an additive manufacturing or othersuitable production system adapted to form a solid representation of theflow conditioning device.
 8. The method of claim 7 wherein said computerprogram is a computational fluid dynamic program.
 9. The method of claim7 wherein said design constraints representative of the input flow arecomprised of pressure distributions.
 10. The method of claim 7 whereinsaid design constraints representative of the input flow are comprisedof pressure or velocity distributions.
 11. The method of claim 7 whereinsaid design constraints representative of the input flow are comprisedof pressure and velocity distributions.
 12. The method of claim 7wherein said design constraints representative of the output flow arecomprised of pressure distributions.
 13. The method of claim 7 whereinsaid design constraints representative of the output flow are comprisedof velocity distributions.
 14. The method of claim 7 wherein said designconstraints representative of the output flow are comprised of pressureand velocity distributions.
 15. The method of claim 7 further includinga design constraint that places the fluid control device perpendicularto the fluid flow.
 16. The method of claim 7 further including a designconstraint that places the fluid control device everywhere perpendicularto the fluid flow.
 17. The method of claim 7 wherein said designconstraints are 1) representative of the input are comprised of pressureand velocity distributions, 2) representative of the output arecomprised of pressure and velocity distributions and 3) place the fluidcontrol device everywhere perpendicular to the fluid flow.
 18. Themethod of claim 7 wherein said computational fluid dynamic program isadapted to make local design changes in angle, chord length andlocation, and thickness to create a final vane design.
 19. The method ofclaim 6 wherein a vane model creates a vane geometry for said vane linesby using parameters including the distance to the nearest two vaneslines and the desired vane thickness and solidity.
 20. The method ofclaim 1 wherein an array of desired velocity vectors is obtained fromcomputational fluid dynamics or measurements from an experiment withinthe input flow.